• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.1
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• pp.85-92
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• 2013

Many efforts will have to be made on securing the stable supply of the energy due to the worldwide trend of controlling the utilization fossil fuels inducing global climate change. Renewable portfolio standard enforced to power companies over 500 MW capacity from 2012. Tidal current energy is one of the most interesting renewable and clean energy resources that have been less exploited. Especially, Korea has worldwide outstanding tidal current energy resources and it is highly required to develop a tidal current energy conversion system(TECS) in coastal region. So, we examine a tidal in-stream energy using a numerical model and estimate a tidal current potential for commercialization of tidal current power plant in the sea of the Bunamgun-do. Available tidal energy resources is also analytically estimated using a tidal farm method and the annual energy production of an optimal TECS arrays will be calculated with taking into account interference of lateral and longitudinal spacing.

• Korean Journal of Optics and Photonics
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• v.3 no.4
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• pp.227-233
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• 1992

The simulation code was developed for the development of the split-disk geometry glass amplifier, which could design the laser apparatus and analyze the properties of the laser system. The flashlamp emission energy at the short wavelength region must be reduced, while maintaining a current density between 2000 and 4000 A/$\textrm{cm}^{2}$, in order to reduce the thermal loading in the laser glass and to raise the coupling efficiency between the emission spectrum of the flashlamps and the absorption spectrum of the laser glass. By cutting the laser glass into three equal pieces, the temperature rise in the laser glass dropped by 70% due to the efficient removal of the heat in the laser glass. It was found that the $Nd^{3+}$ doping rate of each laser glass should be properly selected and the optimum value of the product of the absorption coefficient $\alpha$ and the thickness d of the laser glass is about 0.26 in the split-disk geometry.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.444-444
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• 2011

Recently, patterned magnetic films and elements attract a wide interest due to their technological potentials in ultrahigh-density magnetic recording and spintronic devices. Among those patterned magnetic structures, magnetic anti-dot patterning induces a strong shape anisotropy in the film, which can control the magnetic properties such as coercivity, permeability, magnetization reversal process, and magneto-resistance. While majority of the previous works have been concentrated on anti-dot arrays with a single magnetic layer, there has been little work on multilayered anti-dot arrays. In this work, we report on study of the magnetic properties of bilayered anti-dot system consisting of upper perforated Co layer of 40 nm and lower continuous Ni layer of 5 nm thick, fabricated by photolithography and wet-etching processes. The magnetic hysteresis (M-H) loops were measured with a superconducting-quantum-interference-device (SQUID) magnetometer (Quantum Design: MPMS). For comparison, investigations on continuous Co thin film and single-layer Co anti-dot arrays were also performed. The magnetic-domain configuration has been measured by using a magnetic force microscope (PSIA: XE-100) equipped with magnetic tips (Nanosensors). An external electromagnet was employed while obtaining the MFM images. The MFM images revealed well-defined periodic domain networks which arise owing to the anisotropies such as magnetic uniaxial anisotropy, configurational anisotropy, etc. The inclusion of holes in a uniform magnetic film and the insertion of a uniform thin Ni layer, drastically affected the coercivity as compared with single Co anti-dot array, without severely affecting the saturation magnetization ($M_s$). The observed changes in the magnetic properties are closely related to the patterning that hinders the domain-wall motion as well as to the magneto-anisotropic bilayer structure.

• Journal of the Korean Magnetics Society
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• v.22 no.3
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• pp.97-102
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• 2012

In this paper, a non-contact power transferring has been performed. Power Transferring by using an electromagnetic inductive coupling is more suitable for high power transmission than by using a magnetic resonance method. Power transferring system has been designed with Loading Distribution Method to divide the electric and magnetic loading for designing the magnetic core and electric coil. To design optimum shapes of magnetic yoke, 3D finite element analysis has been performed. Experimental results show good agreement with numerical ones. So, it could be adopted in the electric power transferring system for a short-distance wireless electric power transferring machine.

• Elastomers and Composites
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• v.47 no.3
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• pp.194-200
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• 2012

Rubber components have been widely used in automotive industry as anti-vibration components for many years. These subjected to fluctuating loads, often fail due to the nucleation and growth of defects or cracks. To prevent such failures, it is necessary to understand the fatigue failure mechanism for rubber materials and to evaluate the fatigue life for rubber components. The objective of this study is to develop the durability analysis process for vulcanized rubber components, which is applicable to predict fatigue life at initial product design step. The determination method of nonlinear material constants for FE analysis was proposed. In order to investigate the applicability of the commonly used damage parameters, fatigue tests and corresponding finite element analyses were carried out and strain energy density was proposed as the fatigue damage parameter for rubber components. The fatigue analysis for automotive rubber components was performed and the durability analysis process was reviewed.

• The Journal of the Convergence on Culture Technology
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• v.6 no.2
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• pp.529-534
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• 2020

The development of civilization is in line with evolution of cities and transportation technology caused by industrialization. Up to now, a city has been developed owing to transportation cost reduction and needs for land utilization as a limited core business district. Continuous increase of urban population density has accompanied by lots of problems socioeconomically such as rise of land value, traffic congestion, gap between the rich and poor, air pollution, etc. Those issues are difficult to be solved in existing city ecosystem. However, a clue for solving the problems could be found in there. The design of Seoul mid-night bus route was from analysis of movement of people in the rural area by using ICT so that a city ecosystem should be firstly analyzed for solving rural issues. If the cause of those is found, big data platform construction is required to raise the life quality of citizen and the problems could be solved. Big data should be located in the middle of the platform connected with every element of city based on ICT for real-time collection, analysis and application. This paper addresses construction of big data platform and its application for sustainable smart city.

• Journal of the Korean Association of Geographic Information Studies
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• v.6 no.3
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• pp.21-32
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• 2003

This paper discusses the design of location optimization visualization and feasibility of 3 dimensional visualization techniques. In generic GIS visualization of location analysis, 2 dimensional visualization techniques have been used to map location elements and model solution, such as displaying demand and supply points, drawing connecting lines(e. g. spider line) of optimal locations to their demands, and representing density of location variations. Nevertheless, current GIS and location analysis literatures have little attentions in 3D visualization applications for location optimization problems. Previous research has been neglected 3D visualization of solution performances and its evaluation of solution quality. Consequently, this paper demonstrates potential benefits of 3D visualization techniques and its appropriate GIS applications for location optimization analysis. The visualization effectiveness of 3D approaches is examined in terms of spatial accessibility, and solution performance of optimal location models is evaluated. Finally, this paper proposes extensive 3D visualization perspectives for location analysis and GIS research as a further research agenda.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.6
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• pp.383-389
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• 2001

We report on the design, fabrication, and characterization of 0.35${\mu}{\textrm}{m}$-gate AIGaAs/InGaAs PHEMTs for millimeter-wane applications. The epi-wafer structures were designed using ATLAS for optimum DC and AC characteristics, 0.351m-gate AIGaAs/rnGaAs PHEMTs having different gate widths and number of fingers were fabricated using electron beam lithography Dependence of RF characteristics of PHEMT on gate finger with and number of gate fingers have been investigated. PHEMT haying two 0.35$\times$60${\mu}{\textrm}{m}$$^2$ gate fingers showed the knee voltage, pinch-off voltage, drain saturation current density, and maximum transconductance of 1.2V, -1.5V, 275㎃/mm, and 260.17㎳/mm, respectively. The PHEMT showed fT(equation omitted)(current gain cut-off frequency) of 45㎓ and fmax(maximum oscillation frequency) of 100㎓. S$_{21}$ and MAG of the PHEMT were 3.6dB and 11.15dB, respectively, at 35㎓

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.5
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• pp.46-54
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• 1984

A silicon-gate n-well CMOS process with 3 $\mu$m gate length was developed and its possibility for the applications was discussed,. Threshold voltage was easily controlled by ion implantation and 3-$\mu$m gate length with 650 $\AA$ oxide shows ignorable short channel effect. Large value of Al-n+ contact resistance is one of the problems in fabrications of VLSI circuits. Transfer characteristics of CMOS inverter is fairly good and the propagation delay time per stage in ring oscillator with layout of (W/L) PMOS /(W/L) NMOS =(10/5)/(5/5) is about 3.4 nsec. catch-up occurs on substrate current of 3-5 mA in this process and critically dependent on the well doping density and nt-source to n-well space. Therefore, research, more on latch-up characteristics as a function of n-well profile and design rule, especially n+-source to n-well space, is required.

• The KSFM Journal of Fluid Machinery
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• v.10 no.6
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• pp.32-37
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• 2007

Aerodynamic forces and moments have been used to control rocket propelled vehicles. If control is required at very low speed, Those systems only provide a limited capability because aerodynamic control force is proportional to the air density and low dynamic pressure. But thrust vector control(TVC) can overcome the disadvantages. TVC is the method which generates the side force and roll moment by controlling exhausted gas directly in a rocket nozzle. TVC is classified by mechanical and fluid dynamic methods. Mechanical methods can change the flow direction by several objects installed in a rocket nozzle exhaust such as tapered ramp tabs and jet vane. Fluid dynamic methods control the flight direction with the injection of secondary gaseous flows into the rocket nozzle. The tapered ramp tabs of mechanical methods are used in this paper. They installed at the rear in the rocket nozzle could be freely moved along axial and radial direction on the mounting ring to provide the mass flow rate which is injected from the rocket nozzle. In this paper, the conceptual design and the study on the tapered ramp tabs of the thurst vector control has been carried out using the supersonic cold flow system and schlieren system. This paper provides the thrust spoilage, three directional forces and moments and distribution of surface pressure on the region enclosed by the tapered ramp tabs.